Polymers and glasses are important materials for non-silicon MEMS devices. Precision structuring of such materials has been plagued by the lack of proper tools capable of producing the required intricate details and finish quality. Machining with high peak power, short pulse lasers has become a potential technique for such applications due to the reduced thermal damage, high precision, small feature size and flexibility in pattern generation. In particular, the nanosecond and femtosecond pulsed lasers offer significant advantages with the ability to deposit energy in materials in a very short time interval, hence ensuring efficient conversion of the energy for material removal.
In this paper, the results of using femtosecond laser to process polycarbonate, aluminosilicate glasses and nanosecond laser processing of aluminosilicate glasses are discussed. High quality microchannels in polycarbonate and glass substrates for a bubble switch have been created. The critical dimensions are at the micro scale. No cracks or burrs were observed by a scanning electron microscope (SEM). The major processing variables such as cutting speed, energy fluence and power stability were investigated for their effects on machining quality. Microchannels with sub-micron surface roughness and high-aspect ratios were demonstrated.
Preliminary testing of a bubble switch, which is based on the thermo-capillary effect, confirmed the working principle of the device; but indicated that the channels would have to be more narrower to achieve greater switching speeds.